IGF-1 gene therapy prevents spatial memory deficits and modulates dopaminergic neurodegeneration and inflammation in a parkinsonism model.

Cognitive impairment in Parkinson's disease is considered an indicator of the prodromal stages of this condition, occurring prior to the onset of classic and pathognomonic motor symptoms. Among other factors, neuroinflammation is increasingly recognized as a potential mediator of this neurodegenerative process, and glial cells are directly involved. However, the use of neurotrophic factors is associated with neuroprotection and cognitive improvements. Among all those factors, insulin-like growth factor 1 (IGF-1) has attracted considerable attention. In this study, we aimed to investigate the effect of IGF-1 gene therapy in an early animal model of 6-hydroxidopamine (6-OHDA)- induced parkinsonism. For this purpose, we employed male Wistar rats. The animals were first divided into two groups according to the bilateral injection into de Caudate Putamen unit (CPu):(a) VEH group (vehicle solution) and (b) 6-OHDA group (neurotoxic solution). After that, the animals in each group were divided, according to the bilateral injection into the dorsal hippocampus, in a control group (who received a control virus RAd-DSRed) and an experimental group (who received a therapeutic virus (RAd-IGF1). After three weeks of exposure to 6-OHDA, our study showed that IGF-1 gene therapy improved cognitive deficits related to short-term and spatial working memory, it also increased expression levels of tyrosine hydroxylase in the CPu. In addition, the therapy resulted in significant changes in several parameters (area, perimeter, roundness, ramification, and skeleton ́s analyses) related to microglia and astrocyte phenotypes, particularly in the CPu and dorsal hippocampal areas. Our data support the use of IGF-1 as a therapeutic molecule for future gene transfer interventions, that will contribute to a better understanding of the mechanisms correlating cognitive function and inflammatory process.

Schizophrenia-like endurable behavioral and neuroadaptive changes induced by ketamine administration involve Angiotensin II AT1 receptor.

Schizophrenia is a chronic disease affecting 1% worldwide population, of which 30% are refractory to the available treatments: thus, searching for new pharmacological targets is imperative. The acute and repeated ketamine administration are validated preclinical models that recreate the behavioral and neurochemical features of this pathology, including the parvalbumin-expressing interneurons dysfunction. Angiotensin II, through AT1 receptors (AT1-R), modulates the dopaminergic and GABAergic neurotransmission. We evaluated the AT1-R role in the long-term neuronal activation and behavioral alterations induced by repeated ketamine administration. Adult male Wistar rats received AT1-R antagonist candesartan/vehicle (days 1-10) and ketamine/saline (days 6-10). After 14 days of drug-free, neuronal activation and behavioral analysis were performed. Locomotor activity, social interaction and novel object recognition tests were assessed at basal conditions or after ketamine challenge. Immunostaining for c-Fos, GAD67 and parvalbumin were assessed after ketamine challenge in cingulate, insular, piriform, perirhinal, and entorhinal cortices, striatum, and hippocampus. Additionally, to evaluate the AT1-R involvement in acute ketamine psychotomimetic effects, the same behavioral tests were performed after 6 days of daily-candesartan and a single-ketamine administration. We found that ketamine-induced long-lasting schizophrenia-like behavioral alterations, and regional-dependent neuronal activation changes, involving the GABAergic neurotransmission system and the parvalbumin-expressing interneurons, were AT1-R-dependent. The AT1-R were not involved in the acute ketamine psychotomimetic effects. These results add new evidence to the wide spectrum of action of ketamine and strengthen the AT1-R involvement in endurable alterations induced by psychostimulants administration, previously proposed by our group, as well as their preponderant role in the development of psychiatric pathologies.

Sex frailty differences in ageing mice: Neuropathologies and therapeutic projections.

It is well-established that females live longer than males. Paradoxically, women tend to have poorer health, a condition often named sex frailty. The aim of this study was to evaluate possible frailty predictors in older mice in a sex-specific manner, in order to employ these predictors to follow-up therapy efficiency. To further evaluate therapy effects, we also investigated the use of neurotrophic insulin-like growth factor 1 (IGF-1) gene therapy and its correlation with the expression of this frailty and emotional behaviour. In order to evaluate frailty, we employed two different approaches. We performed a frailty assessment through a 31-Item Clinical Frailty Index and through a Performance-Based 8-Item Frailty Index. Our results show that both indexes are in concordance to evaluate sex differences, but they do not correlate when evaluating IGF-1 therapy effects. Moreover, in order to reduce test-to-test variability for measures of dependent variables, we compared open field results across studies assessing sex and treatment by means of the z-score normalization. The data show that regular open field parameters submitted to z-score normalization analysis could be a useful tool to identify sex differences in ageing mice after growth factor therapies. Taking this into account, sex is a factor that influences the incidence and/or nature of all major complex diseases; the main outcome of our investigation is the development of an efficient tool that compares the use of different frailty index calculations. This represents an important strategy in order to identify sex differences and therapy efficiency in ageing models.

Angiotensin II modulates amphetamine-induced glial and brain vascular responses, and attention deficit via angiotensin type 1 receptor: Evidence from brain regional sensitivity to amphetamine.

Amphetamine-induced neuroadaptations involve vascular damage, neuroinflammation, a hypo-functioning prefrontal cortex (PFC), and cognitive alterations. Brain angiotensin II, through angiotensin type 1 receptor (AT1 -R), mediates oxidative/inflammatory responses, promoting endothelial dysfunction, neuronal oxidative damage and glial reactivity. The present work aims to unmask the role of AT1 -R in the development of amphetamine-induced changes over glial and vascular components within PFC and hippocampus. Attention deficit was evaluated as a behavioral neuroadaptation induced by amphetamine. Brain microvessels were isolated to further evaluate vascular alterations after amphetamine exposure. Male Wistar rats were administered with AT1 -R antagonist, candesartan, followed by repeated amphetamine. After one week drug-off period, animals received a saline or amphetamine challenge and were evaluated in behavioral tests. Afterward, their brains were processed for cresyl violet staining, CD11b (microglia marker), GFAP (astrocyte marker) or von Willebrand factor (vascular marker) immunohistochemistry, and oxidative/cellular stress determinations in brain microvessels. Statistical analysis was performed by using factorial ANOVA followed by Bonferroni or Tukey tests. Repeated amphetamine administration increased astroglial and microglial markers immunoreactivity, increased apoptotic cells, and promoted vascular network rearrangement at the PFC concomitantly with an attention deficit. Although the amphetamine challenge improved the attentional performance, it triggers detrimental effects probably because of the exacerbated malondialdehyde levels and increased heat shock protein 70 expression in microvessels. All observed amphetamine-induced alterations were prevented by the AT1 -R blockade. Our results support the AT1 -R involvement in the development of oxidative/inflammatory conditions triggered by amphetamine exposure, affecting cortical areas and increasing vascular susceptibility to future challenges.

Novel adenoviral IGF-1 administration modulates the association between depressive symptoms and aging: Does gender matter?

Depression is an illness of multifactorial origin and it seems to involve the dysregulation of many physiological processes. It also has been associated with age and a decreased in the expression of some neurotrophins. However, there are not unique animal models to assay depressive-like behavior, with male and females responding differently. In this study, we report the effects of gender on aged associated depressive signs as frailty, muscular strength and motor activity, as well as the role of intramuscular IGF-1 gene therapy in these processes. We found that male mice had higher general discomfort than females. Moreover, we observed that IGF-1 treatment did not modify this index in females. Regarding male mice, adenoviral IGF-1 injection reduced frailty scores compared to its adenoviral control. According to data, IGF-1 gene therapy had a positive effect on depressive associated hypo-locomotion activity as indicate by delta of total distance and the increment observed in time of mobility in male mice. This neurotrophic factor also increased the latency of time to fall in grip strength in male mice compared to female mice. Moreover, we observed that, while the therapy had no effect on the digging behavior, IGF-1 treatment diminished the latency to dig and increase the number of buried marbles in male mice, having no effect on female. The present study demonstrates that, in order to establish an animal model of depression both, gender and age are relevant variables/factors to consider. We also conclude that a frailty phenotype underlies depressive-like symptoms in an experimental mouse model. Furthermore, we demonstrated that intramuscular injection represents a less invasive, feasible and controllable route of IGF-1 gene delivery for the treatment of the depressive phenotype in old mice.

Brain Angiotensin II Involvement in Chronic Mental Disorders.

BACKGROUND: The functioning of the central nervous system is complex and it implies tight and coordinated interactions among multiple components. Neurotransmitters systems imbalance is a hallmark in the central nervous system (CNS) disorders. These pathologies profoundly impact the social, cultural, and economic perspective worldwide. The etiopathology of CNS illnesses is still poorly understood, making their treatment difficult. Brain angiotensin II (Ang II), through its AT1 receptors, modulates dopaminergic, glutamatergic and GABAergic neurotransmission, which are responsible for movement control, cognition, emotions and stress responses. Alterations of these functions, concomitant with modified brain reninangiotensin system (RAS) components, have been described in CNS pathologies like depression, Parkinson, Alzheimer, and schizophrenia. In this sense, altered functionality of angiotensin I converting enzyme and AT1 receptors, is associated with augmented susceptibility to the occurrence of these pathologies. Moreover, some epidemiological data showed lower incidence of Alzheimer disease in hypertensive patients under treatment targeting RAS; meanwhile preclinical studies relate RAS with Parkinson and depression. Little is known about schizophrenia and RAS; however, Ang II is closely related to dopamine and glutamate pathways, which are mainly altered in this pathology. CONCLUSION: The available evidences, together with the results obtained by our group, open the possibility to postulate brain Ang II as a possible therapeutic target to treat the above-mentioned CNS disorders.

Neurovascular unit alteration in somatosensory cortex and enhancement of thermal nociception induced by amphetamine involves central AT1 receptor activation.

The use of psychostimulants, such as amphetamine (Amph), is associated with inflammatory processes, involving glia and vasculature alterations. Brain Angiotensin II (Ang II), through AT1 -receptors (AT1 -R), modulates neurotransmission and plays a crucial role in inflammatory responses in brain vasculature and glia. Our aim for the present work was to evaluate the role of AT1 -R in long-term alterations induced by repeated exposure to Amph. Astrocyte reactivity, neuronal survival and brain microvascular network were analysed at the somatosensory cortex. Thermal nociception was evaluated as a physiological outcome of this brain area. Male Wistar rats (250-320 g) were administered with AT1 -R antagonist Candesartan/vehicle (3 mg/kg p.o., days 1-5) and Amph/saline (2.5 mg/kg i.p., days 6-10). The four experimental groups were: Veh-Sal, CV-Sal, Veh-Amph, CV-Amph. On day 17, the animals were sacrificed and their brains were processed for Nissl staining and immunohistochemistry against glial fibrillary acidic protein (GFAP) and von Willebrand factor. In another group of animals, thermal nociception was evaluated using hot plate test, in the four experimental groups, on day 17. Data were analysed with two-way anova followed by Bonferroni test. Our results indicate that Amph exposure induces an increase in: neuronal apoptosis, astrocyte reactivity and microvascular network, evaluated as an augmented occupied area by vessels, branching points and their tortuosity. Moreover, Amph exposure decreased the thermal nociception threshold. Pretreatment with the AT1 -R blocker prevented the described alterations induced by this psychostimulant. The decreased thermal nociception and the structural changes in somatosensory cortex could be considered as extended neuroadaptative responses to Amph, involving AT1 -R activation.

Brain Angiotensin II AT1 receptors are involved in the acute and long-term amphetamine-induced neurocognitive alterations.

RATIONALE: Angiotensin II, by activation of its brain AT1-receptors, plays an active role as neuromodulator in dopaminergic transmission. These receptors participate in the development of amphetamine-induced behavioral and dopamine release sensitization. Dopamine is involved in cognitive processes and provides connectivity between brain areas related to these processes. Amphetamine by its mimetic activity over dopamine neurotransmission elicits differential responses after acute administration or after re-exposure following long-term withdrawal periods in different cognitive processes. OBJECTIVE: The purpose of this study is to evaluate the AT1-receptor involvement in the acute and long-term amphetamine-induced alterations in long-term memory and in cellular-related events. METHODS: Male Wistar rats (250-300 g) were used in this study. Acute effects: Amphetamine (0.5/2.5 mg/kg i.p.) was administered after post-training in the inhibitory avoidance (IA) response. The AT1-receptor blocker Losartan was administered i.c.v. before a single dose of amphetamine (0.5 mg/kg i.p.). Long-term effects: The AT1-receptors blocker Candesartan (3 mg/kg p.o.) was administered for 5 days followed by 5 consecutive days of amphetamine (2.5 mg/kg/day, i.p.). The neuroadaptive changes were evidenced after 1 week of withdrawal by an amphetamine challenge (0.5 mg/kg i.p.). The IA response, the neuronal activation pattern, and the hippocampal synaptic transmission were evaluated. RESULTS: The impairing effect in the IA response of post-training acute amphetamine was partially prevented by Losartan. The long-term changes induced by repeated amphetamine (resistance to acute amphetamine interference in the IA response, neurochemical altered response, and increased hippocampal synaptic transmission) were prevented by AT1-receptors blockade. CONCLUSIONS: AT1-receptors are involved in the acute alterations and in the neuroadaptations induced by repeated amphetamine associated with neurocognitive processes.